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    Wyświetlanie 1-15 z 15
    Tytuł:
    Aircraft dynamics during flight in icing conditions
    Parametry lotu samolotu w warunkach oblodzenia
    Autorzy:
    Kowaleczko, G.
    Wachłaczenko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/282001.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    ice accretion
    wing icing
    simulation
    Opis:
    This paper presents numerical analysis of airplane motion parameters during wing in-flight icing. The wing external flaps deflection event was taken under consideration. The mathematical model of the airplane motion including twelve ordinary differential equations was employed. Using available publications as well as TS-11 “Iskra” jet trainer geometrical and mass relationships, a computer code evaluating motion parameters of an iced airplane was developed. On the basis of analysis results, conc- lusions referring airplane dynamic properties during wing ice accretion was formulated.
    Praca przedstawia wyniki numerycznej analizy parametrów ruchu samolotu podczas symetrycznego oblodzenia skrzydła oraz usterzenia wysokości w czasie lotu. Pod uwagę wzięto również przypadek wypuszczania klap zaskrzydłowych w czasie występowania oblodzenia. Zastosowano klasyczny model matematyczny dynamiki ruchu samolotu, opisany przez układ dwunastu równań różniczkowych pierwszego rzędu. W odniesieniu do wiadomości zaczerpniętych z literatury oraz danych geometrycznomasowych samolotu TS-11 „Iskra” opracowano program komputerowy do wyznaczania parametrów ruchu z uwzględnieniem oblodzenia samolotu. Na podstawie analizy wyników przedstawiono wnioski opisujące własności dynamiczne samolotu wykonującego lot w warunkach oblodzenia.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2012, 50, 1; 269-284
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Application of GIS and Remote Sensing in a Spatiotemporal Analysis of Coastline Retreat in Rufisque, Senegal
    Autorzy:
    Koulibaly, Cheikh Tidiane
    Ayoade, Johnson O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1838021.pdf
    Data publikacji:
    2021
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    patiotemporal change
    coastline
    erosion
    accretion
    adaptation
    Rufisque
    Opis:
    This paper is aimed at analyzing the phenomenon of shoreline retreat in the locality of Rufisque from 1978 to 2018 mainly using geospatial data and field visits. A set of Landsat images from different dates at 10 year intervals was then acquired through the United States Geological Survey platform and shoreline change analysis was run using the Digital Shoreline Analysis System. In addition to that desktop work, interactions with local residents allowed the determination of ongoing adaptation strategies actually in place to cope with coastal erosion. The study showed that Rufisque is subject to serious rates of erosion reaching −19.48 m/year from 1978–1988, close to −8 m/year from 1988–1998, −5.88 m/year from 1998–2008 and −6.67 m/year from 2008–2018. Beside that coastal erosion, it has been noticed that the coastline also experienced in some of its parts cases of accretion reaching 4.94 m/year for 1988–1998, 7.29 m/year from 1998–2008 and 7.68 m/year during the period 2008–2018. In terms of surfaces, Rufisque’ shoreline respectively lost 156.81 ha (1978–1988), 80.55 ha (1988–1998), 6.94 ha (1998–2008), 12.93 ha (2008–2018) and in the same note gained 2.86 ha (1988–1998), 32.51 ha (1998–2008) and 19.16 ha (2008–2018) attesting to the fact that the coastline is subject to both spatiotemporal changes. Finally, this study also reveals that while authorities’ reaction is taking place at much lower pace, local communities are actually using their ingenuity to put in place strategies to tackle coastal erosion.
    Źródło:
    Geomatics and Environmental Engineering; 2021, 15, 3; 55-80
    1898-1135
    Pojawia się w:
    Geomatics and Environmental Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Shoreline Changes in the Coastal Area of Kuala Terengganu, Malaysia
    Autorzy:
    Subiyanto, Subiyanto
    Ahmad, Ahmad
    Mamat, Mustafa
    Ihsan, Yudi Nurul
    Afrianto, Eddy
    Hidayat, Yuyun
    Supian, Sudradjat
    Powiązania:
    https://bibliotekanauki.pl/articles/1031676.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Crank-Nicolson
    accretion
    coastal development
    erosion
    implicit scheme
    Opis:
    The analysis of shoreline change trends is fundamental to a broad range of investigations undertaken by coastal scientists, coastal engineers, and coastal managers, as well as the government, in this case, the coastal development policy-maker. In order to know the changing of shoreline position around the coastal area of Kuala Terengganu, an analysis and then simulation of shoreline change was performed over, respectively, 2 years, 3 years and 4 years. In this simulation, the longshore distance was divided into 87 cells of length 34 m. Shoreline positions from satellite imagery in 2010 were used in this simulation as the initial condition. Based on the numerical result, both erosion (north side) and accretion (south side) occurred around the Sultan Mahmud Airport, Kuala Terengganu. The average erosion and accretion during the 4 year period is 42.93 m and 40.89 m, respectively.
    Źródło:
    World News of Natural Sciences; 2020, 28; 24-33
    2543-5426
    Pojawia się w:
    World News of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sediment Accretion and Total Organic Carbon Accumulation Among Different Mangrove Vegetation Communities in the Kamora Estuary of Mimika Regency, Papua, Indonesia
    Autorzy:
    Setyadi, Gesang
    Sugianto, Denny Nugroho
    Wijayanti, Diah Permata
    Pribadi, Rudhi
    Supardy, Eddy
    Powiązania:
    https://bibliotekanauki.pl/articles/2028102.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    aerial root
    carbon accumulation
    Mangrove
    Mimika
    Papua
    sediment accretion
    Opis:
    A sediment accretion and carbon accumulation study was carried out in Kamora Estuary, Mimika Regency, Papua Province, Indonesia, to determine the accretion rate and total organic carbon loading in the area as well their correlation with geographical setting and mangrove aerial root type. The sediment stake method was used to measure the elevation changes, whereas the sediment trap method was used to determine sediment accretion and total organic carbon accumulation. Three locations were selected, namely at upstream, middle and downstream the mangrove communities, with each location installed up to 500 m perpendicular to the riverbank. The elevation changes based on sediment stakes were $8.4–12.3 mm$ $year^{-1}$. Sediment accretion based on sediment traps was $18.5–25.4 mm$ $year^{-1}$ or $1.88–2.98 g$ $cm^{-2}$ $year^{-1}$, while the mean total organic carbon accumulation was $736.8 ±169 g$ $m^{-2}$ $year^{-1}$. The results are higher than those of similar studies in other regions, but they are consistent with other studies in Papua New Guinea. This study found that higher sediment accretion occurred at the riverbank compared with the interior area, while the elevation changes were greater in the upstream area. Higher relative density and higher basal area had a negative correlation with sediment accretion, but the number of roots had a positive correlation with sedimentation. The high sedimentation in the Kamora Estuary is resulting in the expansion of the mangrove forest at a rate of $3%$ $year^{-1}$. Assisted mangrove colonization can be applied to expand the mangrove forest, especially considering the use of Rhizophora species, which this study found to be more effective at trapping sediment.
    Źródło:
    Journal of Ecological Engineering; 2021, 22, 11; 142-156
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of Trans-European Suture Zone in Poland: from Ediacaran rifting to Early Palaeozoic accretion
    Autorzy:
    Nawrocki, J.
    Poprawa, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/2058943.pdf
    Data publikacji:
    2006
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Early Palaeozoic
    Trans-European Suture Zone
    Ediacaran, terrane
    rifting
    accretion
    Opis:
    This contribution summarizes selected results of the “Palaeozoic Accretion of Poland” Project. Emphasis is placed on geochronological, geochemical and palaeomagnetic constraints on the Late Neoproterozoic to Early Palaeozoic development of the Trans-European Suture Zone (TESZ). During the Late Neoproterozoic break-up of Rodinia, a major rift developed in the area of the future TESZ along which Baltica was separated from peri-Gondwana and Laurentia, resulting in opening of the Tornquist Ocean and development of the southwestern Baltica passive margin. This was paralleled by the development of the Cadomian orogenic system along the margin of Gondwana and the eastern and southern margins of Baltica. Some tectonic units involved in the TESZ, such as the Brunovistulian Terrane and the Małopolska Massif characterized by Cadomian basement, were derived fromthe internal and external parts of the Cadomian Orogen, presumably somewhere at the SE or SW corners of Baltica. Determination of areas where these terrains were originally located depends strongly on the Ediacaran plate model that is adopted for Baltica. The Małopolska Massif was reaccreted to Baltica, presumably due to latest Ediacaran strike-slip tectonics, during the late Middle to Late Cambrian, causing at that time an interruption of its passive margin subsidence pattern and minor erosion. During Late Ordovician to Silurian times, the Caledonian collision of Gondwana-derived East Avalonia Terrane with Baltica gave rise to the development of a foredeep basin along the southwestern margin of Baltica. The proximal part of this foredeep corresponds to the Pomeranian region to the Koszalin-Chojnice Zone, and its distal parts to the Baltic Basin, both of which developed on Baltica basement. During Ordovician and Silurian times clastics were shed into the Koszalin-Chojnice Zone and the Baltic Basin from the evolving Caledonian orogenic wedge, consisting of a subduction-related volcanic arc, obducted ophiolites and accretionary prism, as well as crustal units that were detached from basement of Baltica and Avalonia. The Brunovistulian Terrane was accreted to theMałopolskaMassif at the turn from the Silurian to the Devonian. Proximal terranes, such as the Pomerania and Łysogóry units remained after Late Neoproterozoic rifting in a position close to the relatively mobile SW margins of Baltica.
    Źródło:
    Geological Quarterly; 2006, 50, 1; 59-76
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stability and safety of ships : holistic and risk approach
    Autorzy:
    Kobyliński, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/2069592.pdf
    Data publikacji:
    2007
    Wydawca:
    Uniwersytet Morski w Gdyni. Polskie Towarzystwo Bezpieczeństwa i Niezawodności
    Tematy:
    maritime safety
    risk analysis
    ship's stability
    ice accretion on ships
    Opis:
    Present stability regulations developed over the years by IMO reached definite conclusion with the adoption of the Revised Draft of the Intact Stability Code. The criteria included there are design criteria of the prescriptive nature, based mainly on statistics of stability casualties. Currently IMO is considering development of criteria based on ship performance. Concept of such criteria is, however, at present not agreed. The criteria are working comparatively well with regard to the majority of conventional ships, however advent of very large and sophisticated ships of non-conventional features caused that those criteria may be inadequate. The author advances the idea consisting of application of safety assessment and risk analysis using holistic and system approach to stability. Safety against capsizing (or LOSA accident) is a complex system where design, operational, environmental and human factors have to be taken into account. Although this seems to be a very complex task, in the opinion of the author it may be manageable and could be applied for safety assessment of highly sophisticated and costly ships.
    Źródło:
    Journal of Polish Safety and Reliability Association; 2007, 2; 211--218
    2084-5316
    Pojawia się w:
    Journal of Polish Safety and Reliability Association
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of ice deposit shape and ice accretion rate on airfoil in atmospheric icing conditions and its effects on airfoil characteristics
    Autorzy:
    Sznajder, J.
    Sieradzki, A.
    Stalewski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/242499.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    aerodynamics
    two-phase flow
    simulation of ice accretion
    aircraft engineering
    transport
    vehicle
    Opis:
    Simulations of ice accretion on airfoil in icing conditions were conducted using ice accretion model implemented by authors in ANSYS FLUENT CFD solver. The computational model includes several sub-models intended for simulations of two-phase flow, determination of zones of water droplets impinging on the investigated surface, flow of water in a thin film on airfoil surface and heat balance in air-water-ice contact zone. The method operates in an iterative loop, which enables determination of effects of gradual deformation of aircraft surface on airflow over the surface, which has impact on distribution of collected water, flow of water film over the surface and local freezing rates. The implementation of the method in CFD solver made it necessary to complement the mathematical model of determination of local rates of deformation of aircraft surface with modification of computational mesh around the surface, which must conform, to the deformed surface. Results of simulated ice accretion on NACA 0012 airfoil were compared with results of experiment conducted in icing wind tunnel for a 420 s long process of ice accretion in steady-flow, steady angle-of-attack conditions. Close agreement of values and location of maximum ice thickness obtained in experiment and in the flow, simulations can be observed. For the airfoil deformed with ice, contour determination of its aerodynamic characteristics at several other angles of attack was conducted proving dramatic degradation of its aerodynamic characteristics due to ice deformation.
    Źródło:
    Journal of KONES; 2017, 24, 2; 271-278
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The issue of icing in aviation. Study with the use of numerical simulation
    Autorzy:
    Grzegorczyk, K.
    Wajszczak, E
    Galas, D
    Powiązania:
    https://bibliotekanauki.pl/articles/102261.pdf
    Data publikacji:
    2013
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    icing
    numerical simulation
    ice accretion
    meteorological aspect of icing
    physics of icing
    Opis:
    Although it has been over 100 years since Wright brothers’ first flight, icing has not been entirely investigated yet. The article is divided into 4 parts. The first one introduces the receiver of meteorological aspect of icing. Second part is devoted to physics aspect of ice accretion. The third and fourth parts describe icing with mathematical models and present a numerical simulation. We have completed our presentation with the results of numerical simulation.
    Źródło:
    Advances in Science and Technology. Research Journal; 2013, 7, 17; 42-46
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ocena morfologii powierzchni stopu Inconel 718 po toczeniu wzdłużnym
    Asessment of morphology of machined surface of Inconel 718 alloy after longitudinal turning
    Autorzy:
    Szablewski, P.
    Chwalczuk, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/194737.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
    Tematy:
    częstotliwość narostu
    węgliki spiekane
    parametry skrawania
    frequency of accretion
    sintered carbide
    cutting parameters
    Opis:
    Celem przeprowadzonych badań było określenie wpływu parametrów skrawania na jakość powierzchni obrobionej podczas toczenia wzdłużnego superstopu Inconel 718 bez udziału cieczy chłodząco-smarującej. Zrealizowane badania posłużyły do określenia częstotliwości powstawania narostu (oblepień) na obrobionej powierzchni podczas obróbki na sucho. Uzyskane wyniki pokazują, że podczas obróbki stopów na osnowie niklu bez udziału cieczy chłodząco-smarującej najkorzystniej jest stosować większe głębokości skrawania i większe wartości posuwu. Podczas przeprowadzonych badań najmniejsze wartości częstotliwości powstawania narostu na powierzchni obrobionej otrzymano przy zastosowaniu najwyższych parametrów skrawania podczas prób, tj. f = 0,21 mm/obr. i ap = 0,3 mm. Z kolei najwyższe wartości częstotliwości powstawania narostu na powierzchni obrobionej otrzymano podczas skrawania z najmniejszymi parametrami, tj. f = 0,05 mm/obr. i ap = 0,05 mm. Rezultaty badań pokazują relację minimalnej grubości warstwy skrawanej z wartością promienia zaokrąglenia krawędzi skrawającej. Uwidacznia się to zwłaszcza przy małych przekrojach warstwy skrawanej.
    The aim of the research was to determine the effect of cutting parameters on the surface quality of Inconel 718 super alloy during longitudinal turning without the use of a lubricant. Completed research was used to determine the frequency of the accretion on the machined surface during dry turning. The results show that during machining of nickel based alloys without using a lubricant, it is preferable to use larger cutting depths and higher feed rates. During the tests, the smallest values of the frequency of accretion on the machined surface were obtained using the highest cutting parameters during the tests, ie. f = 0.21 mm/rev. and ap = 0.3 mm. Whereas the highest values of the frequency of accretion on the machined surface were obtained during the cutting with the lowest parameters, ie. f = 0.05 mm/rev. and ap = 0.05 mm. The results of the study show the relation of the minimum thickness of the cutting layer to the radius on the cutting edge. This is especially visible with small cross-section of the cutting layer.
    Źródło:
    Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika; 2017, z. 89 [295], 3; 379-384
    0209-2689
    2300-5211
    Pojawia się w:
    Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mapping and monitoring erosion-accretion in an alluvial river using satellite imagery – the river bank changes of the Padma river in Bangladesh
    Autorzy:
    Billah, Mohammad Maruf
    Powiązania:
    https://bibliotekanauki.pl/articles/1051516.pdf
    Data publikacji:
    2018-10-15
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    bank line shifting
    geographic information system
    remote sensing
    river bank erosion-accretion
    satellite image
    Opis:
    The Padma river is widely known for its dynamic and disastrous behaviour, and the river has been experiencing intense and frequent bank erosion and deposition leading to the changes and shifting of bank line. In this paper, a time series of Landsat satellite imagery MSS, TM and OLI and TIRS images and are used to detect river bank erosion-accretion and bank line shifting during the study period 1975-2015. This study exhibits a drastic increase of erosion and accretion of land along the Padma river. The results show that from 1975 to 2015, the total amount of river bank erosion is 49,951 ha of land, at a rate of 1,249 ha a−1 and the total amount of accretion is 83,333 ha of land, at a rate of 2,083 ha a−1. Throughout the monitoring period, erosion-accretion was more pronounced in the right part of the river and bank line had been shifting towards the southern direction. The paper also reveals that the total area of islands had been increased significantly, in 2015 there was about 50,967 ha of island area increased from 20,533 ha of island area in 1975, and the results evidence consistency of sedimentation in the river bed.
    Źródło:
    Quaestiones Geographicae; 2018, 37, 3; 87-95
    0137-477X
    2081-6383
    Pojawia się w:
    Quaestiones Geographicae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of water collection on two- and three-dimensional aerodynamic surfaces in external two-phase flow in atmospheric conditions
    Autorzy:
    Sznajder, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/244126.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    flow simulations
    aerodynamics
    two-phase flow
    simulation of ice accretion
    aircraft engineering
    transport
    vehicles
    Opis:
    Simulations of two-phase flow cases consisting of air and water dispersed in atmosphere were conducted using ANSYS FLUENT solver. The computational model was built with the aim of determination of zones of water droplets impinging on the investigated surface, which is a first step towards simulations of ice accretion in flow conditions where super cooled water is present as dispersed phase. It follows Eulerian approach, currently most effective approach for determination of distribution of water collection on two- and three-dimensional surfaces. Dispersed water is treated as continuous phase and its transport equations are being solved along with air flow equations in the whole computational domain. There are two specific factors of this two-phase flow problem. One of them is ratio of air and water density, which is a cause of existence of two time scales in obtaining a numerical solution of this problem: one for convergence of air flow solution and another for solution of flow of dispersed water in the computational domain. This required development of a specific strategy in obtaining a numerical solution in some circumstances important in aerodynamics, especially at high angle of attack with flow recirculation zones on the wing. The other factor is relatively low concentration of water droplets in conditions important for atmospheric icing. The consequence of this is possibility of uncoupling of solution for both phases and narrowing the solution of the phase of dispersed water to a small region of non-uniformity of velocities of the dispersed phase. Results for two objects: an airfoil and helicopter tail rotor blade, exploiting the developed computational strategy will be presented.
    Źródło:
    Journal of KONES; 2016, 23, 1; 369-376
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of rime icing and its effects on aerodynamic characteristics of an airfoil
    Autorzy:
    Sznajder, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/243475.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    computational fluid dynamics
    aerodynamics
    two-phase flow
    simulation of ice accretion
    heat exchange
    aircraft engineering
    transport
    vehicle
    Opis:
    A mathematical model for simulation of icing dedicated to simulation of ice accretion and its effects on aircraft aerodynamic characteristics in conditions of rime icing is presented. Pure rime icing occurs at lower temperatures than glaze icing and results in higher roughness of the surface of deposited ice. The model accounts for increased surface roughness, in terms of equivalent sand grain roughness, caused by deposited rime ice, which influences generation and dispersion of heat in the boundary layer. Increase of surface roughness is determined by analytical models created upon experimental data obtained in icing wind tunnels. Increased generation of heat is a result of increased tangential stress on the surface and is quantified in the temperature recovery factor determined numerically by a CFD solver. Effects of surface roughness on the intensity of forced convection are quantified by application of Colburn analogy between heat and momentum transfer in the boundary layer, which allows assessment of heat transfer coefficient for known friction coefficient, determined by CFD. The computational method includes determination of the surface distribution of mass of captured water in icing conditions. The model of freezing of captured water accounts for generation of heat due to latent heat of captured water droplets, temperature recovery in boundary layer and kinetic energy of captured droplets. The sinks of heat include forced convection, heating of super cooled droplets, conduction of heat through the ice layer and sublimation. The mathematical model is implemented as user-defined function module in ANSYS Fluent solver. The results include effects of deposited ice, including increased surface roughness on aerodynamic characteristics of an airfoil.
    Źródło:
    Journal of KONES; 2018, 25, 3; 437-443
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessment of Shoreline and Associated Landuse/Land cover Changes along Part of Lagos Coastline, Nigeria
    Autorzy:
    Akinluyi, F. O.
    Adebola, A. O.
    Adeseko, A. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/100826.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Śląski. Wydział Nauk o Ziemi
    Tematy:
    shoreline changes
    Land use
    Land cover
    LULC
    accretion
    erosion
    Lagos
    linia brzegowa
    zmiany
    pokrycie terenu
    użytkowanie terenu
    erozja
    Nigeria
    Opis:
    The city of Lagos, Nigeria has undergone rapid increase in population due to economic and commercial activities. As a result of this, there has been a persistent change in Land use/Land cover (LULC) of the city and shoreline through the years. This observation necessitated the use of multi-temporal satellite data to characterize shoreline changes between 1984 and 2016. Therefore, the study attempts to determine the shoreline change during the study period and the coastal land use and land cover (LULC) of the study area. Satellite data was acquired and subjected to some image processing techniques such as image enhancement, supervised classification, and shoreline extraction. The digital shoreline analysis system (DSAS) in ArcGIS environment was utilized to cast transects and calculate statistical parameters for the shoreline and spatial data used was Landsat TM, ETM and OLI for the years 1984, 1990, 2000, 2004 and 2016 respectively. The results indicate that LULC changes in built-up areas increases rapidly during the years (1984-2015) from 12.2 -36.2%, water bodies increased from (1984-1990-2000) from 52%, 54%, 52% and reduces to 47.4% in the year 2015 while vegetation cover reduces drastically through the year range from 36%, 33%, 29%, 24% and 16%. A total of 1034 transects were generated with 100m spacing and the average rate of change was calculated for the 32 year period (1984-2016). The linear regression rate (LRR) shoreline result shows a mean of -0.59m/year where 73.1% of transect fall under erosion and 61.8% accretion respectively. The end point rate (EPR) and net shoreline movement (NSM) analysis revealed mean shoreline change of -0.57m/year and -18.1m/period respectively from 1984-2016. The EPR and NSM results both revealed that 231 transect or 22.3% experienced erosion, and 805 transect or 77.9% with accretion. It was observed that significant accretion rate recorded along most sections of the shorelines is attributed to beach nourishment activities.
    Źródło:
    Contemporary Trends in Geoscience; 2018, 7, 1; 59-71
    2299-8179
    Pojawia się w:
    Contemporary Trends in Geoscience
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badania laboratoryjne nad doborem środków przeciwakrecyjnych do płuczek wiertniczych
    Laboratory tests on the selection of anti-accretion agents in water-based drilling muds
    Autorzy:
    Błaż, Sławomir
    Powiązania:
    https://bibliotekanauki.pl/articles/1835026.pdf
    Data publikacji:
    2019
    Wydawca:
    Instytut Nafty i Gazu - Państwowy Instytut Badawczy
    Tematy:
    płuczka wodnodyspersyjna
    akrecja zwiercin
    oblepianie świdra
    skały ilasto-łupkowe
    water-based drilling mud
    cutting accretion
    bit balling
    clay shale rock
    Opis:
    Podczas wiercenia otworów w formacjach łupkowych bardzo często występują poważne problemy związane z niestabilnością otworu wiertniczego. Większość z nich nie wynika z niskiej wytrzymałości mechanicznej przewiercanych skał, ale z ich chemicznie reaktywnego charakteru. Reaktywne skały ilasto-łupkowe pod wpływem płuczek wodnodyspersyjnych ulegają hydratacji. Uwodnione zwierciny przywierają do powierzchni świdra i metalowych części przewodu wiertniczego (rury płuczkowe, obciążniki), tworząc w ten sposób plastyczną mieszaninę, która przeciwdziała bezpośredniemu stykaniu się części wiercącej świdra z powierzchnią urabianej skały. Nadmierny wzrost zawartości rozmokniętej ilastej mieszaniny plastycznej na świdrze i przewodzie wiertniczym wpływa na proces wiercenia poprzez zwiększenie momentu obrotowego. W wyniku zwiększonego oporu może nastąpić przychwycenie przewodu, pogorszenie wskaźników hydraulicznych, co wpływa na zmniejszenie prędkości wiercenia otworu (ROP). W artykule przedstawiono badania nad doborem i wdrożeniem dodatku do wodnodyspersyjnych płuczek wiertniczych nowego rodzaju środka przeciwakrecyjnego zapobiegającego oblepianiu świdra i akrecji zwiercin na przewodzie wiertniczym. Badania skuteczności doboru środków do płuczek wiertniczych były prowadzone według założonej i opracowanej charakterystycznej metodologii badania, uwzględniającej wpływ poszczególnych czynników na zredukowanie zjawiska akrecji. Przeprowadzono szereg testów akrecyjnych określających wpływ rodzaju przewiercanej skały, czasu ekspozycji zwiercin na działanie płuczki, wpływ wielkości powstających zwiercin oraz występującego mechanicznego obciążenia na zjawisko akrecji. Badania doboru środków przeciwakrecyjnych prowadzono na próbkach skał odkrywkowych w środowisku wodnodyspersyjnych płuczek wiertniczych. Uzyskane wyniki zostały poddane analizie, umożliwiającej opracowanie składu środka przeciwakrecyjnego, który może być wykorzystywany jako dodatek do wodnodyspersyjnych płuczek wiertniczych zapobiegający oblepianiu świdra i akrecji zwiercin. Zastosowanie opracowanego środka do płuczek otworowych pozwoliło na ponad 90-procentowe zredukowanie akrecji zwiercin w porównaniu do płuczek bez dodatku tego typu środków. W badaniach potwierdzono także jego znacznie wyższą efektywność w stosunku do obecnie stosowanego w polskim wiertnictwie środka do zapobiegania oblepianiu świdra.
    In the course of borehole drilling through shale formations very often there are serious problems associated with the instability of the borehole. Most of these problems do not result from the low mechanical strength of the drilled rocks, but from the chemically reactive nature of the rocks. Reactive shale-clay rocks are hydrated under the influence of water-based drilling muds. Hydrated cuttings at the bottom of the borehole adhere to the surface of the bit and metal parts of the drill string (drill pipes, drill collars), forming a plastic mixture that prevents direct contact between the drill blades and the surface of the rock to be cut. The excessive increase in the contents of the clayey plastic mixture on the bit and the drill pipe affects the drilling process by increasing the torque. As a result of the increased resistance, the pipe may get stuck, hydraulic indicators may deteriorate, which reduces the rate of penetration (ROP). This article presents research on the selection and implementation of a new type of anti-precipitation agent to water-based drilling muds, preventing the sticking of the bit and accretion of cuttings on the drill string. The selection of anti-accretion agents was carried out ac-cording to the methodology considering the influence of individual factors to reduce the accretion phenomenon. A number of accretion tests were carried out to determine the effect of the type of rock used, the exposure time of the drill cuttings to drilling mud influence, the impact of the size of the formed cuttings and the mechanical load on the accretion phenomenon. Studies on the selection of anti-accretion agents were carried out on open-pit rock samples in the environment of water-based drilling muds. The obtained results were analyzed allowing the formulation of the anti-accretion composition, which can be used as an additive to water-based drilling muds, preventing the drilling bit from getting stuck and the accretion of cuttings. The use of the developed agent has allowed for more than 90% reduction of accretion of drill cuttings compared to muds without the addition of this type of agent, as well as its much higher efficiency than the anti-accretion agent used .in the Polish drilling industry.
    Źródło:
    Nafta-Gaz; 2019, 75, 5; 265-274
    0867-8871
    Pojawia się w:
    Nafta-Gaz
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    "Narastanie miasta" na przykładzie Pragi. Fenomen i dynamizm czeskiej stolicy w XIX i pierwszej połowie XX w.
    "Accretion of the city" on the basis of prague. The phenomenon and dynamism of the Czech capital city in the 19th and the first half of the 20th century
    Autorzy:
    Tkaczewski, Dariusz
    Powiązania:
    https://bibliotekanauki.pl/articles/590696.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Ekonomiczny w Katowicach
    Tematy:
    „Narastanie miasta”
    Fenomen i dynamizm
    Praga
    XIX-XX w.
    „Accretion of the city”
    19th and 20th centuries
    Phenomenon and dynamism
    Prague
    Opis:
    Praga (cz. Praha) to w opinii wielu miasto niezwykłe, magiczne i klimatyczne, o niesamowitym genius loci. To nie tylko legendarna czeska stolica, piękna „Złota Praga” pełna urokliwych zaułków i imponujących zabytków, które powstały w ciągu dziesięciu wieków jej „trwania i narastania”. Współczesna Praga to prężny środkowoeuropejski ośrodek polityczny, administracyjny, ekonomiczno-biznesowy (przemysłowy, handlowy i usługowy) oraz naukowy i akademicki, jak również kulturalny i turystyczny o znaczeniu międzynarodowym. Celem niniejszego artykułu jest przybliżenie fenomenu Pragi jako „magicznego miasta” o zachowanej tysiącletniej tkance miejskiej; będzie w nim mowa o „narastanie miasta” oraz jego dynamizmie cywilizacyjnym XIX i pierwszej połowy XX w., mających niejednokrotnie swe praprzyczyny w niezwykłej historii czeskiej metropolii, a także w jego otwartości na przybyszów.
    Prague (Praha) is widely regarded as an amazing, magical city with lots of ambience and of extraordinary genius loci. It is not only the legendary Czech capital city or gorgeous „Golden Prague” abounding in charming lanes and impressive sights which come from ten centuries of continuance and accretion. Modern Prague is indeed a major Central European political, administrative, business and economic (industrial, commercial or service) centre with cultural and tourist attractions of international importance. This paper seeks to explore the remarkable phenomenon of Prague as a magical city with its preserved thousand-year-old urban fabric; addressing the issue of the accretion of the city and its civilizational dynamism and growth of the 19th and the first half of the 20th century frequently triggered by the stormy yet marvellous history of the Czech metropolis and its openness to newcomers.
    Źródło:
    Studia Ekonomiczne; 2016, 303; 183-202
    2083-8611
    Pojawia się w:
    Studia Ekonomiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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